This invention relates generally to article imprinting apparatus for imprinting information upon packages, cartons and the like as they travel successively spaced along the reach of a conveyor. More particularly, there is provided an improved impact type reciprocating imprinting apparatus which is more durable and versatile and less costly to fabricate, assemble and maintain than prior devices, which enables the employment of pre-inked ink cartridges and markedly increases the useful life thereof by having means for effecting sealing off of the cartridges during all but the actual imprinting stroke of the apparatus.
In particular, the apparatus provided by the invention includes an imprinting head carrying a biased releasably mounted type holder on which type font can be secured. An effective seal is established between the imprinting head and a disposable inking cartridge to prevent evaporative loss from the cartridge, except during the momentary translation of the head along a path leading to an angularly displaced imprinting location whereat the imprinting is performed. Drive and guide (idler) linkage means are provided to direct the imprinting head along said path in an imprinting stroke and a return stroke to resume the sealed engagement.
Known devices capable of imprinting information upon surfaces of packages, cartons and the like conveyed spaced along a given path along the reach of the conveyor generally are of complex construction with accompanying expense of manufacture, fabrication, assembly and maintenance. Two major types of devices are employed in imprinting indicia on packages and the like. One type of device includes a rotary imprinting wheel on which the type font can be mounted for repeated inking by rotary ink transfer means to which ink is supplied from a source thereof, the imprinting wheel intercepting the article to be imprinted. The second major type of imprinting apparatus involves stamping or impacting inked type face means repeatedly upon successively arriving articles.
The type face means are supplied with ink by impacting the type face means upon an ink saturated pad or the like, usually supplied by some storage means such as cartridge or the like, which include an ink impervious body having a window through which access to the ink impregnated pad is enabled.
The invention herein is concerned with the repeatable impact type imprinting apparatus which involves substantial frequency of required maintenance, and particularly the short life of the inking means employed. Frequent and time-consuming ink cartridge replacement is the rule. One reason for such short cartridge useful life may be attributed to the unusually fast drying character of the ink employed. These highly volatile inks evaporate rapidly, usually depleting the ink pad after only a short time or leaving an inking surface which quickly becomes hard and dry, preventing the normal capillarity effect to resupply the surface of the pad. This phenomenon is encountered where the ink supply takes the form of an ink-saturated absorbent pad disposed within a disposable cartridge having access window means to accommodate the printing head. Often, the skin formed by solvent evaporation is hard whereby ink is unevenly applied to the type font, or at least, is insufficient to effect uniform marking of the package, etc.
During the course of the operation of the imprinting apparatus, the imprinting head is disposed substantially longer at the rest condition, engaged against the inking pad surface. The translation of the imprinting head to the imprinting location and application of the imprint occupies minimal time and requires little exposure of the inking pad. Nevertheless, substantial reduction of the effectiveness of the inking means results since evaporation, etc. occurs while the type holder (carried by the imprinting head) is engaged with the inking pad of the ink storing cartridge.
Seals have been attempted with mixed results. Some attempts have interfered with the inking of the type font while others have been ineffective, failing to establish an effective seal.
It should be noted that the ink-saturated pad is generally resilient because of its saturated condition and the character of the ink absorbent material used to form the pad. The area of engagement of the imprinting head as well as the surface of the head engaging the pad is sometimes so resilient as to fail to establish an effective seal. The type holder seated on the imprinting head and effectively constituting same also is not well suited to make a proper seal with the ink-saturated pad or its surrounding border defining lining member, where provided. Accordingly, rapid evaporation of the fast drying ink still materially reduces the useful life of available cartridges requiring removal of the exhausted cartridge and replacement with a fresh cartridge. Often such premature disabling of the ink supply cartridges occurs many times during a normal (average) imprinting run regardless of the number of articles imprinted.
Another problem encountered with the employment of imprinting apparatus of the type described hereinabove involves the formation of a hard skin formed on the pad as a result of evaporation. The skin prevents transfer of ink from the pad, even though there is substantial ink remaining within the impregnated storing pad. This results in premature removal and replacement of the cartridge long prior to depletion of the ink stored therein.
Still another difficulty encountered with a marking device such as described above involves the means employed to effect the translation of the imprinting head to the imprinting position and return. It is known to employ pivotable arms and the like to mount an imprinting head for repeated movement. Ordinarily, these arms are coupled to a source of dynamic power, such as a fluid operated hydraulic or pneumatic system coupled through a signalling device to a drive arm, in turn secured to an imprinting head and/or to the mounting therefor. Known drives cause the imprinting head to be translated from its rest condition to its angularly displaced position at the imprinting location, so that the imprinting head assumes an orientation with its center line perpendicular to the surface upon which imprinting is to be effected.
It is difficult to maintain the head in the proper path to prevent deviation therefrom during translation to and return from the imprinting location. There has been considerable difficulty in achieving the proper orientation of said imprinting head as well as in controlling the contact pressure exerted by the imprinting head both upon the package surface and upon the ink-saturated pad. Where the contact pressure at impact is too great, smearing and/or other blurring of the imprint would be encountered. Often the imprinting head would be misoriented during its imprinting contact with the package surface, resulting in partial imprints, or imprints carrying too much ink, notwithstanding the fast drying nature of the inks employed. The return stroke often strongly impacts in the relatively soft, yieldable surface of the ink-saturated pad whereby to cause splashing of ink fouling the apparatus, the imprinting head and carrier therefor, and often causing ink to be thrown outward, fouling the ambient surroundings.
Accordingly, it would be highly desirable to prevent the above adverse occurrances in a relatively simply constructed marking apparatus, and to include therein, means to prevent evaporative loss by establishing an effective sealed engagement between the ink cartridge and the printing head during all but the actual imprinting.
Another way of reducing ink loss is to control the impact or contact pressure exercised by the imprinting head (the type face carried thereby) upon the saturated inking pad. Often one had to elect between a contact pressure at impact sufficient to assure proper inking and reduction of contact pressure to prevent splashing of ink.
Control of the quantity of ink applied to the type font during each inking step has been found to be difficult. Too much ink applied to the type will result in smearing of the imprint. Applying too little ink will result in unsatisfactory faint imprints. Additionally, the force of impact upon the surface to be imprinted should be carefully controlled to assure proper, clear and sharply defined imprints. Effecting of such controls as applied to the mechanical drive means is expensive and less than satisfactory.
The translation of the imprinting head between the pair of angularly displaced operating positions should be effected by mechanisms which are relatively simple in construction and are effective to assure proper orientation of the type carried by the imprinting head both on the ink saturated pad during the rest condition, and during the time period when momentarily displaced therefrom to effect application of the imprint. Facility in servicing the imprinting apparatus also is a desirable feature not readily available with known imprinting devices of this type. Particularly, removability of both the inking cartridge and the type holder for replacement, change or reorientation would be highly desirable.
In view of the relative complexity of available imprinting apparatus of the type described, there has been a considerable and long felt need to effect reductions in the costs of fabricating, assembly and maintenance without reduction in efficiency and with achieving increased versatility of the apparatus. It also would be highly desirable to provide a marking apparatus which is versatile and capable of being mounted for operation universally in a plurality of orientations with facility and with efficiency and a minimum of maintenance downtime.
In addition, it would be highly advantageous to provide an intermittent impact reciprocable type imprinting apparatus which is capable of operation at relatively high speed without loss in effectiveness.